Firefighting techniques increasingly involve the use of larger diameter hoses and hose couplings to improve the delivery rate at the fire site. As technology in all areas have improved over the years, hoses, nozzles, and other firefighting equipment can be made lighter and stronger, and techniques improve. This makes it possible to deliver higher volumes of water which is one of the most crucial factors in effective fire fighting.
There are several large valves that are used on firetrucks, and in some instances on fire hydrants. The valve disclosed herein is one that is used on the firetruck at the inlet to control water that is flowing from the fire hydrant into the fire engine's fire pump. Previously, a valve of typical construction would have a hinged gate that would swing into seated position to stop the water flow. This type of valve is advantageous in that the gate can be moved completely clear of the valve throat to permit maximum use of the internal diameter of the valve.
However, with larger diameter hoses and fittings, and the accompanying increase in flow rate, larger valves are required so that a bottleneck in the system is not caused by the valve. As the valve gets larger, waterflow increases and the forces experienced by the valve are increased proportionately to the increase in the valve's interior surface area. These valves must be built to withstand tremendous forces, running to several hundred pounds per square inch, and could run close to a thousand pounds per square inch were it not for the pressure relief valve in worse-case water hammer situations.
For these reasons, the flap-type valve used on smaller hoses is not ideal for larger diameter hoses that are becoming more popular. 5" and even 6" diameter hoses are in use. The forces that these high-flow systems exert on the valve flap are tremendous as the valve is being opened or closed. There is a need for a high-volume, high-pressure valve utilizing a different mechanism than the hinged gate.